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(11) | EP 0 423 763 A3 |
(12) | EUROPEAN PATENT APPLICATION |
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(54) | X-ray fluorescence imaging of elements |
(57) A system for detecting the presence of known materials in a body or container. The
system incorporates a gamma or X-ray source for irradiating the body with gamma rays
to produce X-ray fluorescence of materials contained therein. A directionally discriminate
X-ray detector is positioned to intercept X-rays emitted from the body and is adapted
to pass only those X-rays having a predetermined wavelength and incident from a specific
direction that are characteristic of a material of interest contained in the body.
The detector includes a dislocation free single crystal having substantially parallel
input and output surfaces. A second crystal aligned parallel to the first crystal
may be disposed at a position offset from the first crystal to receive the X-rays
transmitted by the first crystal in order to discriminate between materials fluorescing
within the body. In a specific embodiment of the invention, the first detector comprises
an elongated crystal which pass X-rays in accordance with the Borrmann effect. A
plurality of the crystals are arranged in a linear array and the container is either
scanned with the array or the container passed linearly past the array. The detected
X-rays are measured in intensity and the data is processed by suitable data processor
to generate a video image indicative of the presence and shape of the specific materials
for which the system is adapted. In yet another specific embodiment of the invention,
a plurality of such arrays can be arranged with the input surfaces of the crystals
disposed at different Bragg angles to simultaneously detect the presence of a selected
group of materials. |